1. Field of the Invention
The present invention relates to a light-emitting element assembly and a method for manufacturing the same.
2. Description of the Related Art
In a surface emitting laser element, for example, an active layer having a multiquantum well structure is provided in a cavity held between two mirror layers (Distributed Bragg Reflector layers, DBR layers) which are provided on a substrate in the thickness direction thereof, and light emitted from the active layer (light-emitting portion) due to current injection is enclosed to cause laser oscillation. Such a surface emitting laser element uses a cylindrical mesa structure as disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2001-210908. Specifically, a cylindrical mesa structure with a diameter of about 30 μm may be formed, for example, on the basis of a dry etching process or the like. The mesa structure has a laminated structure including, for example, an n-type compound semiconductor layer, an active layer (light-emitting portion), and a p-type compound semiconductor layer. Then, the p-type compound semiconductor layer is partially oxidized from the side of the mesa structure to provide a current-narrowing region in a central portion of the p-type compound semiconductor layer. Then, the mesa structure is coated with an insulating layer, the top of the p-type compound semiconductor layer is partially removed, and a p-side ring electrode is formed in the periphery of the top of the p-type compound semiconductor layer. In addition, an n-side electrode is formed on the back surface of the substrate. By providing such a current-narrowing region, high-efficiency current injection into the active layer may be achieved. A surface-emitting laser element having such a structure permits high-efficiency current injection into the active layer and light-efficiency laser oscillation.
Further, a current is injected into the active layer through the two mirror layers provided above and below the active layer and composed of compound semiconductor layers. However, such mirror layers have low thermal conductivity and thus do not effectively radiate heat generated in the active layer. As a result, there occurs the problem of decreasing the emission efficiency of the surface emitting laser element. Therefore, a surface emitting laser element of related art has a structure in which it is mounted on a sub-mount serving as a heat sink with a solder so that a p-side electrode faces downward, as disclosed in FIG. 4 and paragraph [0048] of Japanese Unexamined Patent Application Publication No. 2003-086895.